Decubitus or pressure ulcers, generally known as bedsores, are common for patients who are paralyzed or otherwise bedridden for extended periods of time. They can result from numerous factors. For example, pressure exerted by a mattress on bony portions or projections of the body, such as the shoulder blades, the ischials, or the heels, can lead to the development of decubitus ulcers. Specifically, the compression of tissues caused by the force of a bone against a surface, such as a mattress, can compromise blood circulation in the compressed tissue, which can result in an ulcer or pressure sore.
Additionally, shear exerted on a patient by a mattress can also contribute to the development of decubitus ulcers by resisting the relatively free movement of the patient's skin as the patient moves around on the mattress or otherwise slides relative to the mattress based on the influence of gravity. Such is particularly true for bedridden patients in gatched or adjustable beds (for example, where the head, middle, and/or foot sections of the bed frame are movable relative to one another). In such situations, for example, as the head section of the bed is raised to an elevated position, gravitational forces can cause a patient's body to slide relative to the mattress and “down” toward the foot of the bed. Even if the amount of sliding is minimal, shear forces exerted by the mattress can lead to ulcers and a variety of other skin-related issues.
Various shear layers or liners are known that are designed to reduce shear exerted on a patient's skin in order to decrease the likelihood of the development of decubitus ulcers. Other apparatus are also intended for the generally improved support of a patient, with resulting beneficial effects. Examples of patent documentation generally relating to such area include U.S. Pat. No. 7,555,796, entitled “Pressure Relieving Mattress;” U.S. Pat. No. 7,444,707, entitled “Shear Reducing Chair Cushion;” U.S. Pat. No. 7,100,229, entitled “Shear Reducing Mattress System;” U.S. Pat. No. 6,425,635, entitled “Weight-shifting Reclining and Tilting Wheelchair Seat;” U.S. Pat. No. 5,802,646, entitled “Mattress Structure Having a Foam Mattress Core;” and U.S. Design Patent No. D502,350, entitled “Shear Reducing Mattress;” and U.S. Patent Application Publication No. 20090144911, entitled “Pressure Relieving Mattress;” U.S. Patent Application Publication No. 20080263776, entitled “Low Air Loss Moisture Control Mattress Overlay;” and U.S. Patent Application Publication No. 20050081300, entitled “Two-mode Therapeutic Mattress System.”
It has been recognized that a shear layer that covers the entire mattress, in an attempt to eliminate all shear forces along the length of a patient's body, may also have the effect of causing a patient to slide all the way down to the foot of the bed as the head section is elevated. Thus, the patient may slide down the mattress until the patient's feet contact the footboard. Such an event would tend to unnecessarily increase pressure on the patient's feet, and could also prevent sliding of the mattress cover relative to the shear layer. Additionally, such shear layers may also cause the mattress cover to bunch up as the patient slides down the mattress, which can further prevent sliding of the mattress cover relative to the shear layer and actually increase the amount of shear forces exerted on a patient's skin.
Accordingly it would be advantageous to address such problems in the prior art by providing a mattress cover that reduces shear forces exerted on the areas of a patient's body that relatively speaking are most likely to develop decubitus ulcers, and that redirects such shear to other areas of the body to avoid the undesired effects of a shear layer or liner that completely covers an entire mattress.